On 4 October 2017 Australian mainstream media began to publish articles predicting increases in summer temperatures, with 50C extremes becoming common by the end of the century.
The articles spoke of associated increased health risks and heat-related urban infrastructure stress. They mentioned a study published in the science journal Geophysical Research Letters.
Given much of the Australia population experienced the heat extremes of the summer of 2015 these articles should have been speaking to believers when it came to the impact of climate change.
Instead on that Wednesday the comments section of many of the online versions of these articles were choked with anti-science, anti-climate change sentiments. None of those making negative comments appear to have read the research mentioned.
A year earlier, on 26 September 2016, ABC News had reported:
A survey of more than 2,000 Australians by the Climate Institute has found 77 per cent believe climate change is occurring and 90 per cent believe the Federal Government has a responsibility to drive action on it.
The research showed most Australians trust the scientific evidence of climate change and believe there are job and investment opportunities in renewable energy.
If recent reader comments in mainstream media are any indication believers are now becoming a relatively silent majority.
Have they lost heart in the face of successive national leaders like the blindly destructive Abbott and weak-kneed Turnbull?
BACKGROUND
Lewis, S., King, A, & Mitchell, D. (2017) Australia's unprecedented future temperature extremes under Paris limits to warming:
Abstract
Record-breaking temperatures can detrimentally impact ecosystems, infrastructure, and human health. Previous studies show that climate change has influenced some observed extremes, which are expected to become more frequent under enhanced future warming. Understanding the magnitude, as a well as frequency, of such future extremes is critical for limiting detrimental impacts. We focus on temperature changes in Australian regions, including over a major coral reef-building area, and assess the potential magnitude of future extreme temperatures under Paris Agreement global warming targets (1.5°C and 2°C). Under these limits to global mean warming, we determine a set of projected high-magnitude unprecedented Australian temperature extremes. These include extremes unexpected based on observational temperatures, including current record-breaking events. For example, while the difference in global-average warming during the hottest Australian summer and the 2°C Paris target is 1.1°C, extremes of 2.4°C above the observed summer record are simulated. This example represents a more than doubling of the magnitude of extremes, compared with global mean change, and such temperatures are unexpected based on the observed record alone. Projected extremes do not necessarily scale linearly with mean global warming and this effect demonstrates the significant potential benefits of limiting warming to 1.5°C, compared to 2°C or warmer.
Plain Language Summary
Extreme temperatures affect ecosystems, infrastructure, and human health. Understanding how climate change is impacting climate extremes and how extremes will change under future global warming are important scientific research questions. Previous scientific studies have focused on how current temperature extremes have been impacted by climate change, or on how the frequency of these current extremes will change in the future. This study takes a different approach and examines how the severity of future temperature extremes might change in the future. We assess the possible severity of Australian temperature extremes under the limits to warming that are described in the Paris Agreement (1.5{degree sign}C and 2{degree sign}C of global warming above the period prior to industrialization). This study finds that the magnitude of future temperature extremes for Australia does not necessarily increase at the same rate of global warming. The severity of possible future temperature extremes simulated by climate models in this study poses serious challenges for preparedness for future climatic change in Australia. For example, daily temperature extremes of 3.8{degree sign}C above existing records are simulated for Australian states, even under the ambitious Paris efforts to curb global warming.
Lewis, S., King, A, & Perkins-Kirkpatrick, S. (2017) Defining a New Normal for Extremes in a Warming World:
Abstract
The term “new normal” has been used in scientific literature and public commentary to contextualize contemporary climate events as an indicator of a changing climate due to enhanced greenhouse warming. A new normal has been used broadly but tends to be descriptive and ambiguously defined. Here we review previous studies conceptualizing this idea of a new climatological normal and argue that this term should be used cautiously and with explicit definition in order to avoid confusion. We provide a formal definition of a new climate normal relative to present based around record-breaking contemporary events and explore the timing of when such extremes become statistically normal in the future model simulations. Applying this method to the record-breaking global-average 2015 temperatures as a reference event and a suite of model climate models, we determine that 2015 global annual-average temperatures will be the new normal by 2040 in all emissions scenarios. At the regional level, a new normal can be delayed through aggressive greenhouse gas emissions reductions. Using this specific case study to investigate a climatological new normal, our approach demonstrates the greater value of the concept of a climatological new normal for understanding and communicating climate change when the term is explicitly defined. This approach moves us one step closer to understanding how current extremes will change in the future in a warming world.
Lewis, S. & King, A. (2015) Dramatically increased rate of observed hot record breaking in recent Australian temperatures:
Abstract
Persistent extreme temperatures were observed in Australia during 2012–2014. We examine changes in the rate of hot and cold record breaking over the observational record for Australia- and State-wide temperatures. The number of new hot (high-maximum and high-minimum temperatures) temperature records increases dramatically in recent decades, while the number of cold records decreases. In a stationary climate, cold and hot records are expected to occur in equal frequency on longer than interannual time scales; however, during 2000–2014, new hot records outnumber new cold records by 12 to one on average. Coupled Model Intercomparison Project phase 5 experiments reveal increased hot temperature record breaking occurs in simulations that impose anthropogenic forcings but not in natural forcings-only experiments. This disproportionate hot to cold record breaking rates provides a useful indicator of nonstationarity in temperatures, which is related to the underlying mean observed Australian warming trend of 0.9°C since high-quality records began in 1910.
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